1. Field of the Invention
One embodiment of the present invention relates to an insulating pattern and a method of forming the insulating pattern. One embodiment of the present invention relates to a light-emitting device using electroluminescence (EL) and a method of manufacturing the light-emitting device. One embodiment of the present invention relates to a lighting device.
2. Description of the Related Art
A method of forming a thin film pattern is known in which an inverted tapered or T-shaped insulating pattern which has an eaves portion is formed to be used as a separation layer for dividing a film (hereinafter, referred to as “separation layer”). Specifically, a separation layer having an eaves portion is formed and a thin film is formed thereover, whereby a thin film pattern can be formed in which the thin film is not formed in a region covered by a projecting part of the separation layer and the thin film is physically divided.
A method (lift-off method) is well known in which by applying the above technique, a conductive thin film is used as a thin film formed over a separation layer and the separation layer is removed after the thin film is formed, whereby only a conductive thin film pattern remains.
As a method of forming an inverted tapered separation layer, a method in which a negative photosensitive resin is used, light exposure is performed, and development is performed is known.
As a method of forming a T-shaped separation layer, a method (manufacturing method 1) is known in which the amount of light to which a negative photosensitive resin is exposed is smaller and the time of development treatment is shorter than in a usual method, whereby a T-shaped separation layer is formed (Patent Document 1).
As another formation method, a method (manufacturing method 2) is known in which resins with different photosensitivities are stacked, light exposure is performed separately for each of the upper resin and the lower resin with the use of different light-exposure masks, and then development treatment is performed, whereby a T-shaped separation layer is formed.
Further, an organic EL element has been actively researched and developed. In the fundamental structure of the organic EL element, a layer containing a light-emitting organic compound is interposed between a pair of electrodes. By applying voltage to this element, light can be emitted from the light-emitting organic compound.
The organic EL element can be formed into a film form; thus, a large-area element can be easily formed. Therefore, the organic EL element has a high utility value as a surface light source that can be applied to lighting or the like.
For example, a lighting device including an organic EL element is disclosed in Patent Document 2.